Primary hypomagnesemia

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Primary hypomagnesemia with hypercalciuria and nephrocalcinosis with severe ocular involvement

ORPHA:2196Clinical subtype

Also called FHHNC with severe ocular involvement · Hypercalciuria-bilateral macular coloboma syndrome · Meier-Blumberg-Imahorn syndrome

What it is

Familial primary hypomagnesemia with hypercalciuria and nephrocalcinosis with severe ocular involvement (FHHNCOI) is a form of familial primary hypomagnesemia (FPH), characterized by excessive magnesium and calcium renal wasting, bilateral nephrocalcinosis, progressive renal failure and severe ocular abnormalities.

Key facts

Prevalence
<1 / 1 000 000 (Europe)
Age of onset
Childhood
Inheritance
Autosomal recessive
Classified as
Clinical subtype

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

Gene

CLDN19Disease-causing germline mutation(s)

ICD-10 codes

E83.4filed under a broader ICD-10 category — shared with 9 other rare diseases

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references

GARD 3451MESH C565423MONDO 0009548OMIM 248190UMLS C1855466

Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.

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